Since its launch on March 27 -- the first day of the Macworld/iWorld Conference in San Francisco -- Microsoft’s much anticipated Office for iPad has received overwhelmingly positive reviews. One great feature is that once you’ve downloaded Office for iPad, you can download Word, PowerPoint and Excel absolutely free to start viewing documents stored on your tablet.

Related: Hey, iPad Users: You Can Finally Download Microsoft Office

The catch? If you want to edit or create new documents, you’ll need an MS Office 365 subscription -- and that means a series of important decisions regarding which version of Office 365 is right for you. The successor to Microsoft’s Business Productivity Online Suite, Office 365 is a subscription-only online office and software-plus-services package that offers varying access -- depending on the version you select and the licensing -- to services and software such as messaging, collaboration, email, calendaring, file sharing, communications, etc.

Look carefully before you leap. Multiple subscription plans and price points featuring different levels of functionality are available for various size deployments of Office 365. Microsoft currently offers two versions of Office 365 for small business for up to 25 users, one version for midsize businesses for up to 300 users, and 11 different options at the enterprise level for 250 or more users. At the enterprise level, there are three options designed for education enterprises and four each for government and private enterprise. There is also a single plan for non-profits. In short, there is a version of Office 365 for every size of business.

At first blush, you may zero in on an Office 365 version that seems suited to your needs based on size, but beware -- the licensing for Office 365 can be extraordinarily complex, with dozens of new SKUs or part numbers for the many Office 365 offerings. For instance, neither of the small business options offers compliance features such as data loss prevention, e-discovery and premium journaling, so small businesses with compliance requirements may need to choose Office 365 Midsize Business or higher.

Related: 4 Ways the 'New' Microsoft Is Dramatically Different From the 'Old' Microsoft

Key factors to consider in selecting an office 365 package. Determining which plan to subscribe to ultimately depends on your starting point -- current environment -- and your objective -- your anticipated environment. Before you take the plunge with Office 365, take some time to consider a few important questions:

  • How many users must be supported? Each Office 365 option is designed for specific user population sizes, so you may be ineligible for some options.
  • Will the user base increase? Migration from certain smaller versions to larger ones is not supported by Microsoft, so plan carefully.
  • Where are the users located? Office 365 is not offered worldwide, although major markets in North America, Europe and Asia are currently supported.
  • What functionality is required? Each higher version of Office 365 offers additional features, so you can choose based on your functional needs.
  • Am I replacing on-premise functionality, or augmenting it? Office 365 provides rapid update frequency, which raises the issue of how that might affect home-grown applications that are tightly coupled with Office applications. By ceding deployment, support and update authority to Microsoft, an organization is essentially relinquishing control over certain aspects of their operations -- perhaps mission-critical operations -- to the procedures and practices of Microsoft.
  • How much will my ideal Office 365 option cost? Costs range from $5 per month per user for the basic Small Business option ($60 charged annually) to $22 per user per month with an annual commitment for the Enterprise E4 edition. All 14 options can be explored here.

As mobile apps continue to become more prevalent for both business and personal use, devices such as the iPad and software solutions such as Office for iPad and Office 365 will become increasingly important -- and unavoidable. The tradeoffs may include higher software costs and a degree of lost control over certain enterprise operations on one side, but enterprises can gain a fully managed environment capable of supporting business and staff.

Related: Why Moving to the Cloud Should Be Part of Your Business Plan