The 180 days is the period during which your Sounds libraries (for SampleTank, Syntronik etc) are initially available to download. Once downloaded and installed they (and your software) can be used for ever (or at least until your system fails).
After the 180 days, if you need to download the libraries again you would need to pay a single Downloads Reactivation fee ($10? less JamPoints) for a further 180 days availability of all your libraries. IK Multimedia recommends that, once downloaded, you back-up the downloaded files, so you do not need to download them again or pay the fee. (Again, unless you back-up disk fails.)
