The free storage tier used to be one of the largest in the industry at 15GB absolutely free. In 2015 Microsoft announced that they were going to lower their free offering back to 5GB's and gave user the chance to claim the 15GB's by acknowledging that they want it. If you have not made that effort to claim the extra storage you will need to make sure you are not using more than 5GB’s because you will lose anything above that if you don’t pay their $1.99/month fee for the next step up of 50GB’s.
The smaller space will be for all new users so if you don’t have an account yet, all new users will get 5GB’s for free. Microsoft is in the middle of the pack of other options from competitive companies. Of course if you have made the move over to Office 365 the amount of storage you will have starts at 1TB for personal space. This for most people is more than adequate for most users. Let us know your thoughts about these changes.